In order to test the wear resistance of a sample material, such as plastic, resin, or other material, a blade can be dragged across the surface of the sample. The depth and visibility of the scratches can be judged to determine which material is more resistant to scratching.
An example conventional scratch test machine includes five blades, each blade attached to a metal arm, is pulled across the surface of a sample. The design allows different loads to be placed on the arms, in order to determine at which load the sample scratches. In a conventional scratch test machine, hydraulic pressure within a cylinder is adjusted so as to approximately determine the test speed. However, such scratch tests are often irreproducible. Improved surface testing machines are required, in order to obtain more accurate and reproducible surface testing results.